In the words of Llyod Morgan, “Evolution is the name we give to the comprehensive plan of sequence in all natural events”. Thus, evolution refers to a sequence of different natural phenomena. It points out that there are a sequence and system in different phenomena of nature. But then, the system has been interpreted differently by different scientists and philosophers who advocate evolutionary theories. Before the advent of the theory of evolution, it was believed that God has created the world at a particular time. According to Christianity, God created the different species of living beings on Sunday about four thousand years before Christ. It was believed that different species of living beings have been born as such and God has made man in his own image. The greatest defect in this non-evolutionary theory is that it does not explain sequence in natural phenomena nor does it show any purpose in them. On the other hand, the theory of evolution shows continuity and sequence in different phenomena of nature which is more suitable to explain the purpose inherent in it.
Types of Evolution:
The theory of evolution is a gift of science. Though a man had been experiencing continuity and sequence in his own evolution since time immemorial, historically it was in the eighteenth century that it was known by scientific discoveries that the universe has evolved and passed through different stages in evolution. The theory of evolution since then had been utilized in many fields. The following are the main types of evolution-
Cosmic Evolution- This includes the description of the evolution of the world, sun, moon, planets, stars, etc.
Terrestrial Evolution- This type of evolution describes the different changes which gradually occurred in our planet.
Geological Evolution- This describes different geological changes.
Biological Evolution- This shows a gradual advent of different species of living beings, and also the extinction of several species.
Human Evolution- This type of evolution explains changes in human civilization, culture, literature, art, religion etc.
The foremost problem in evolution is concerning the cause of it. Is evolution purposive or is it mechanical? According to some thinkers, it is mechanical and without any purpose. These believe in mechanical evolution and include philosophers like Laplace, Spencer, Darwin, Lamarck, Weismann and Driesch etc. On the other hand, according to some thinkers there is some conscious power behind evolution and evolution serves its purpose. Important among the advocates of purposive evolution are Lloyd Morgan, Bergson, Samual Alexander, Whitehead and Sri Aurobindo in India.